Hi Jump Kick causes damage. If your Pokémon misses with this attack, it
will lose just 1 Hit Point (not 1/8 of the damage it would have
dealt, as is often reported).

If the attacker strikes first in the round and KOs itself as a result
of this attack, the enemy will completely lose the chance to do anything
that round. The next round will begin normally, and the opposing trainer
will have the option to choose an attack or switch out the enemy Pokémon,
as usual.

Note that if the Pokémon that replaces the attacker also strikes first,
the attacking trainer will get at least two attacks in a row without
response. This is particularly important if the enemy was trying to use a
healing move at the time of the initial attack.

Other than the lost turn, the enemy will suffer no other detrimental
effects. It will not be charged a PP for the attack it didn't get to
use, and it will not be subject to recurrent poison, burn, or Leech Seed damage, since those penalties
are only enforced after the affected Pokémon attacks.

Considering that the attacker only receives recoil damage if it
misses, there is no strategical benefit to KOing oneself when
using this attack.